Key Conditions for Optimum Fermentation

[Jason Stone]

As any wise man and Beatles fan will tell you, a good thing will happen if you let it be – may it be love, a tender rack of barbecued ribs or, in the case at hand, fermentation.

Enter yeasts, living microorganisms that readily grow in sugary solutions, produce enzymes (sucrose and zymase) that break up sugar or starch, and convert it into ethyl alcohol and carbon dioxide gas. (Saccharomyces cerevisiae is the superstar species of yeasts, instrumental to baking, brewing, winemaking, and other such vital enterprises since ancient times.)

The process of turning sugar into ethyl alcohol and carbon dioxide uses up almost 95% of the sugar, making these the chief products of fermentation. The remaining 5% of sugar contributes to the simultaneous formation of several by-products: impurities such as glycerol, volatile acids, fusel oils, ethers, aldehydes, esters. These substances not only make for great band names, but also give character to ethyl alcohol with ever fascinating flavors and colors. The downside, alas, is that they’re also responsible for hangovers.

This is why, with fermentation, you have to let it be – but in the right conditions. Here are the key factors you should keep an eye on:

1. Temperature: high temperatures kill the yeast, low temperatures decreases their activity. The higher the temperature, the faster the rate of fermentation, but the lower the alcoholic yield. The optimum temperature is 78º F. Never exceed 90º F.

2. Proportion: the optimum sugar to water ratio is 2 pounds to 1 gallon.

3. Yeast and time: the usual proportion is 1 cup yeast to 5 gallons of water. At this ratio, in the right conditions, the yeast will produce enough ethyl alcohol to stop fermentation in 14 days. Yeast reproduces rapidly in sweet solutions, so less is better, but it will take a little longer for active fermentation to get going. Stand by your mash, and let experience guide you.

4. Vinegar inhibition: when exposed to oxygen, the mash or wine will tend to promote the growth of another fungi that will manufacture vinegar. No oxygen, no vinegar.

5. Settling time: when fermentation is complete, the mash or wine will be turbid and must settle. Settling will take several days or a week, even months in the case of wine. Chilling the fermented mash and/or filtering it will speed the process. Siphon or decant the clear solution and discard sediment. Try not to aerate the mash or wine unnecessarily, thereby risking the formation of vinegar.
After fermentation, the mash will be no more than 16% and usually not less than 3% ethyl alcohol by volume. It’s a dilute alcohol solution, so now’s the time to crank up your whiskey still and distill in high spirits.

Happy distilling!

[Danespirit]

Temperature: high temperatures kill the yeast plants

Yeast are not plants as such, they are unicellular microorganism.
Like all living creatures they are eukariotic, which means their cells is build around a central nucleus.
So are multicellular organisms like mamals (including the homo sapiens distillerus).
Most yeast will reproduce happily from 5 C to around 30 C.
Below that the yeast goes into a kind of stasis, this is why you can store dry yeast for months in your fridge.
Significant higher than 30 C yeast starts to die, at 80 C most living organisms loose their integrety of their cells.
With 50 G normal yeast i can have 3X15 L to ferment without problems.
I am sure i could even divide it up to four portions, still having activity within two hours.
Dry yeast will take longer as the cells are in stasis mode.
I usually let them start up in a cup with luke warm water and a teaspoon of sugar.
So having one package dry yeast as a backup in my fridge, i always have enough to start at least three ferments in 15 L containers.

[HDNB]

Thems some pretty broad statements. i'm posting on a hunch this will get interesting quickly.

btw, vinegar in my research, comes from acetobacter (copy and paste into address bar) :http://en.wikipedia.org/wiki/Acetic_acid_bacteria

I'd be interested to learn about a fungus that synthesizes vinegar the same way the bacterium does.

[Jesse]

My take is these broad statements are all being made with the singular goal of high ethanol production in mind? Or are you after the most neutral beverage/wash? As you know, different temperatures, sugar concentrations (proportions as you called it here), yeast strains, pitching rates, etc will all affect flavors as well, and it can't be said that there is a single value for any of them that is appropriate for all of the different things we're trying to do here.

The ideal sugarhead is fermented differently than the ideal Czech Pilsener, which will be different still from the ideal barley-malt whiskey.

I do, however, agree with your general approach to yeast. You seem to have a respect for them which anyone making beer/wine/spirits/mead/cider/sourdough/etc. should share.

[DAD300]

Nothing of ph yet, hmmmm

All my experiments point towards temp and ph being right for the strain of yeast and then the sugar concentration. And how about feeding sugar in stages?

[3d0g]

1. Temperature: high temperatures kill the yeast plants, low temperatures decreases their activity. The higher the temperature, the faster the rate of fermentation, but the lower the alcoholic yield. The optimum temperature is 78º F. Never exceed 90º F.

Plants? 78F is the optimum temp for *all* yeasts? Fascinating...

2. Proportion: the optimum sugar to water ratio is 2 pounds to 1 gallon.

1.094 OG is optimum? Hmm...

3. Yeast and time: the usual proportion is 1 cup yeast to 5 gallons of water. At this ratio, in the right conditions, the yeast will produce enough ethyl alcohol to stop fermentation in 14 days. Yeast reproduces rapidly in sweet solutions, so less is better, but it will take a little longer for active fermentation to get going. Stand by your mash, and let experience guide you.

1 cup, eh? Mr. Malty begs to differ. And 14 days? why did all the ferments @ the distillery I worked at finish in 4-5 days? Wonder what we were doing wrong...

4. Vinegar inhibition: when exposed to oxygen, the mash or wine will tend to promote the growth of another fungi that will manufacture vinegar. No oxygen, no vinegar.

Fungi? Oh, and there's plenty of anaerobic LAB. Some of them are pretty darn important to whiskey flavors too.

5. Settling time: when fermentation is complete, the mash or wine will be turbid and must settle. Settling will take several days or a week, even months in the case of wine. Chilling the fermented mash and/or filtering it will speed the process. Siphon or decant the clear solution and discard sediment. Try not to aerate the mash or wine unnecessarily, thereby risking the formation of vinegar.
After fermentation, the mash will be no more than 16% and usually not less than 3% ethyl alcohol by volume. It’s a dilute alcohol solution, so now’s the time to crank up your whiskey still and distill in high spirits.

If you only got 3% (1.071 FG, 23% attenuation) you've *completely* failed in fermentation.

[Brutal]

Can't buy entertainment like this.

[Danespirit]

Nothing of ph yet, hmmmm

All my experiments point towards temp and ph being right for the strain of yeast and then the sugar concentration. And how about feeding sugar in stages?

I often "feed" the little fellows with sugar in stages. The fermentation goes more even without violent production of CO2.
Yeast functions on a broad range of PH between 2,5 and 8,0.
In the case of to low PH, yeast tends to produce sediment that layers on the bottom

Yeast mainly divides into Saccharomycses and non Saccharomycses: (see below).

Saccharomyces:

Cerevisiae var.
bayanus
cerevisiae
chevalieri
oviformis
ellipsoides
capensis
uvarum

Non-Saccharomyces:

Schizosaccharomyces
Zygosaccharomyces
Hansenula
Hanseniaspora
Kloeckera
Dekkera
Brettanomyces
Debaromyces
Rhodotorula
Pichia
Torulaspora
Candida
Cryptococcus
Kluyveromyces
Metschhnikowia

Edit: Optimum temperature for yeast fermentation is in the range of 32 C to 35 C, that would be 89,6 F to 95 F
As ethanol accumulates, the optimum temperature range to maximize ethanol growth becomes more narrow.

[woodshed]

3dog said it for me.

I love when folks establish absolutes with a lack of info to back them up.

[Ferment_It]

I decided not to post earlier...

Most has been pointed out already but I'd like to point out that he has yeast that can chew up starch! Man I've been doing it wrong this whole time. Woodshed you can keep my enzyme order, I'm just goin to pick up some of his yeast!

This guy sells stills. Gotta wonder what kind of info he's selling his customers...

[Danespirit]

Oh..didn't i mention them on my list..?
It's a newly discovered kind, they are called: Saccharomyces Terminatorix..
They are extremly violent and eat everything. Put your fingers in, and they are history (no fingers in the ferment anyway).
Sorry...couldn't help myself..

[NgrainD]

This part tho....
[quote="Jason Stone"] and let experience guide you.

This part was $money$.

That's exactly what I've done since I started this lifestyle, I've let all this combined experience on this site guide me. The more I read, the more I realize.. I need to read.

[ranger_ric]

The whole post is just a copy & paste off of his website...

http://www.whiskeystill.net/blogs/whisk ... rmentation" onclick="window.open(this.href);return false;" rel="nofollow

[thecroweater]

Hmm 32' to 35'c pretty tight range. Ale yeasts will be cactus much past 25 or 26'c and the best range for most Coopers brand yeast is 27' to 29'c. You may find also a lot of rum guys like to run their washes hot in the 35'.to 38'c range to achieve the flavours they are chasing . Temps vary a lot due to the strain, the ferment and the intended result,

[Tater]

Lets Play Nice.

[woodshed]

I see where your going Tater but feel like we have been pretty nice. The postulation of the OP just does not add up.
The OP's declarations are not accurate and should be corrected.

[Danespirit]

Hmm 32' to 35'c pretty tight range. Ale yeasts will be cactus much past 25 or 26'c and the best range for most Coopers brand yeast is 27' to 29'c. You may find also a lot of rum guys like to run their washes hot in the 35'.to 38'c range to achieve the flavours they are chasing . Temps vary a lot due to the strain, the ferment and the intended result,

Yes indeed it seems high Croweater..
Anyway a company that bought the yeast production from Danisco (former Danske spritfabrikker), worked out a chart for this.
They supply distilleries all around the world with yeast, so i think they are credible on that subject.

It makes sense when you look at the temperature vs alcoholproduction.
This chart also consolidates the rule of thumb, that you get the best yield out of it if the alcoholconcentration is between 7-10% ABV.
Anything higher than that and yeast will start to die rapidly.
Now..normal fermenting temperature for me would be 18 to 22 C (higher in the summer) and i like a slow and even ferment.
The less one stresses the yeast, the better endproduct one get.
I will attach a Pdf file of it, to verify my statement.

Sidenote: The companys name is Lallemand.
I laught my ass of as i read that, cause in danish "lalle" is to talk nonsense and tumble around, and mand= man.
Couldn't have had a better name...

Yeast thermostability Document.pdf

(1.16 MiB) Downloaded 151 times

[scuba stiller]

Can't buy entertainment like this.

+1

[thecroweater]

Yes I know this company and I know some of their products (I have their yeast here). Regardless ale yeast is developed to ferment longer and colder as a rule and i know plenty of rum guys that will run hotter than that range because they like the flavours produced by heat stressed yeast in run. Horses for courses.

[Bobdoe]

The whole post is just a copy & paste off of his website...

http://www.whiskeystill.net/blogs/whisk ... rmentation" onclick="window.open(this.href);return false;" rel="nofollow

Yup.
Two points I'd like to make (that hopefully will be found constructive)
"Enter yeasts, living microorganisms that readily grow in sugary solutions, produce enzymes (sucrose and zymase)"- well, sucrose isn't an enzyme, its a disaccharide made up of one molecule of glucose hooked to one of fructose. Sucrose is good old table sugar and is commonly added to our mash unless one is doing the malted AG approach. Sucrose will spontaneously hydrolyze to free glucose and free fructose in acidic water, and the yeast themselves can also internalize sucrose and then break it into glucose and fructose.

Basically, this is a very common high school science fair project: Measure the CO2 production by yeast when they are supplied different kinds of sugar, like pure glucose (also called dextrose), or pure sucrose (table sugar), or pure maltose, or pure lactose, etc. An example of the experiment shown here:

https://faculty.unlv.edu/debelle/lab/196/energetics/" onclick="window.open(this.href);return false;" rel="nofollow
and here's an image from that site:

Friends, the yeast do not directly metabolize table sugar (sucrose) to EtOH and CO2 in the absence of O2. It uses glucose; table sugar (sucrose) has to be broken down into glucose and fructose first. The sugar (sucrose) that has been used for centuries in mash of course works fine, because as mentioned above, sucrose does get converted to glucose (and fructose). If we add glucose the process is faster. But sucrose is dirt cheap and we buy it in any grocery store. Glucose (dextrose) can be easily found for purchase but probably will not really make our final product any better. Glucose also does not taste as sweet as sucrose.

As for Zymase: Zymase was coined in the late 1800's (won the dude who discovered the pathway the Nobel Prize!). Zymase was a complex mixture of many enzymes, and today we know that yeasts metabolize glucose (the monosaccharide we make when we mash) into EtOH using about 11 different enzymes catalyzing 11 different reactions, the last reaction making EtOH.

There will be a quiz on this material on Monday.

Respectfully,

Bobdoe

[Bobdoe]

Oh..didn't i mention them on my list..?
It's a newly discovered kind, they are called: Saccharomyces Terminatorix..
They are extremly violent and eat everything. Put your fingers in, and they are history (no fingers in the ferment anyway).
Sorry...couldn't help myself..

I had to comment on this! I've seen pictures of people touring Maker's Mark and they are sticking their fingers in the ferment! Encouraged to taste it! Yes, sticking their dirty mitts into the ferment and tasting it. Whaaaaaaaaa!?! Yuck.

See it here
http://golftravel.about.com/od/kenucky/ss/makers_3.htm" onclick="window.open(this.href);return false;" rel="nofollow


Bobdoe

[3d0g]

I had to comment on this! I've seen pictures of people touring Maker's Mark and they are sticking their fingers in the ferment! Encouraged to taste it! Yes, sticking their dirty mitts into the ferment and tasting it. Whaaaaaaaaa!?! Yuck.

Seriously, what's the problem with that? Nothing off their "dirty mits" is going over the lyne.

[Bobdoe]

Ya, I know. Good point 3 Dog. But I know someone who's visited MM and you just don't know where her fingers have been!
BD

[Tater]

I see where your going Tater but feel like we have been pretty nice. The postulation of the OP just does not add up.
The OP's declarations are not accurate and should be corrected.

Ya have and agree .Just want it to a correction over a beating.

[Jason Stone]

Oh dear.. Well ..Let's hope that I'm more knowledgeable in making a whiskey still than the key conditions for optimum fermentation.
Thank you guys for all the information you have provided and happy distilling! Admin edit (removed ad )

[Swedish Pride]

quite a blatant way to try to get folks here to get a still of you don't you think?

[ranger_ric]

+1 SP